The present invention generally relates to vehicle controls, and more particularly to a thrust management and interface for aircraft during taxi operations.
Conventionally, aircraft may taxi by thrusting the engines at low levels with the landing gear down. The resultant thrust pushes the aircraft forward. Using the aircraft engines burns jet fuel. Jet engines may operate with less efficiency at lower settings. Since an aircraft may spend hours a day in the taxi phase of a flight plan, excess fuel costs may be directly tied to the taxi phase.
Some aircraft may incorporate electric taxi (eTaxi) systems which move aircraft along taxi ways during the taxi phase. The eTaxi systems may electrically drive the wheels with a motor. An eTaxi system may work well on smaller aircraft whose weight may not overload the wheels. However, on larger aircraft, the weight of the aircraft and increased frictional force may impede wheel rotation under current electric drive capabilities. For example, an eTaxi system may not provide enough impetus to produce sufficient momentum for an aircraft to move from a dead stop (such as at the start of taxiing). Larger aircraft may also encounter points along the taxi way that increase the load on the wheels (for example, dips in the road or slippery conditions which may cause wheel slippage). The aircraft's momentum is thus reduced sometimes to a halt.
Increasing the current to the electric motor may not produce enough torque to regain momentum and in some cases may overdrive the motor into failure.
One approach may require a pilot to use the eTaxi system separately from the engine(s) during taxiing. The pilot may restart engines on need when eTaxi systems are insufficient. Typically separate throttle controls may be dedicated to the eTaxi and engine systems. The pilot may often have to guess as to how much of each throttle source is needed at any given point along the taxi phase. As may be appreciated, having to engage separate throttle systems for the same phase of the flight plan may require increased focus and potentially may raise the possibility of pilot error. In addition, starting and re-starting of engines increases the hazard of potential fire. Aircraft engines are known to produce fireballs or flare-ups during engine start-up. Typically, a crew is present during the initial start-up of the aircraft to combat flames. However, a crew may not follow the aircraft along the taxi way. Thus, restarting engines along different points of the taxi way may produce a dangerous situation.
Also, in smaller aircraft that use eTaxi systems, engine starting may need 3 minutes before the aircraft is allowed to takeoff from the runway. The engine start-up process increases the potential for fire hazard out on the runway. It may become difficult for fire fighting vehicles and personnel to access the aircraft out on the runway during a fire emergency. Also, there are times when an engine may develop starting issues and may never start. In this case, the aircraft has to be taxied back into the apron area for maintenance. Turning the aircraft around may be labor intensive and may cause significant delays to other aircraft queued up to take off behind the immobilized aircraft.
As can be seen, there is a need to provide an improved approach to thrusting an aircraft during taxi operations. In addition, it can be seen that the pilot may benefit from simplifying the interface during taxi operations.